Dynaco Stereo 416 Power Amplifier

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add-on capacitor bank schematic for the ST-416. You may want to right-click (Mac users click/hold) to save these, as they will slow your browser down significantly.


The Dynaco Stereo 416 is a basic two channel power amplifier employing all silicon solid state devices. They include 70 transistors, 51 diodes, 16 light emitting diodes, 2 silicon controlled rectifiers and 8 integrated circuits. The series-parallel connection of 8 output transistors per channel is of full complementary symmetry design. The entire main amplifier is direct coupled. Its measured distortion levels approach the threshold of the most exacting laboratory test equipment, not only at the commonly specified full power ratings, but more importantly at very low power outputs as well. This is the result of circuit techniques which eliminate any discernible crossover notch at low levels, and contributes to the Stereo 416's freedom from listening fatigue. Its lucid, utterly uncolored neutrality reveals delicate nuances and musical shadings in the best pogram material - one result of achieving unconditional stability with varying loudspeaker loads.

Implicit in the design of a superb power amplifier is the responsibility to include superior techniques of protection for both the amplifier and the speaker load, if long-term trouble free operation is to be achieved. To this end, Dynaco has included more separate protective systems and features than have ever been employed in such a product.

These include an AC line circuit breaker (rather than a fuse); four separate power supply fuses; electronic volt-amp limiting to ensure safe operation of the output transistors; independent high temperature cutouts on each channel, which are mounted directly on the output transistors to assure maximum sensitivity; over 1000 square inches of radiating area for the mammoth heat sink; two-speed fan cooling with optimum efficiency; delayed turn-on to eliminate loudspeaker thumping; relay protection against DC signals at the output; load (speaker) protection fuses accessible on the front panel; input level controls to reduce sensitivity; input filters to control the bandwidth; and the exclusive DYNAGUARD™ adjustable dynamic power limiting circuit to protect the speaker load; and a switch to by-pass the level controls, filters, and Dynaguard.

The Stereo 416 was engineered to accomodate a wide range of specialized needs in studio, laboratory and industrial applications, as well as in the home. It has been designed as two independent 200 watt (at 8 ohms) amplifying channels with a common power supply having a high degree of inherent regulation. For special requirements, a technician can easily convert it to a monophonic 600 watt (at 8 ohms) output.

The front panel with handles is designed for mounting in a standard 19 inch rack, and Light Emitting Diodes with range switch provide accurate readout of power. An alternative power transformer for international AC line voltages, and an accessory C-100 Energy Storage System, are available at additional cost.


Power Output Ratings:Less than 0.25% total harmonic distortion at any power level up to 200 watts continuous average power per channel into 8 ohms (300 watts per channel into 4 ohms; 100 watts per channel into 16 ohms) at any frequency between 20 Hz and 20 KHz with both channels driven. Distortion reduces at lower levels.

Power at Clipping, single channel, 2500 Hz, less than 1% distortion:

235 watts @ 8 ohms;
350 watts @ 4 ohms;
135 watts @ 16 ohms.

Intermodulation Distortion: Less than 0.1% at any power level up to 200 watts rms per channel into 8 ohms with any combination of test frequencies. Distortion reduces at lower power levels. Typically less than 0.03%.

Half-Power Bandwidth: 100 watts per channel at less than 0.25% total harmonic distortion from 5 Hz to 35 KHz into 8 ohms.

Frequency Response:

+0, -1 dB, 8 Hz - 50 KHz @ 1 watt into 8 ohms;
±0.5 dB, 20 Hz - 20 KHz @ 200 watts.

Hum and Noise: Greater than 95 dB below rated output, full spectrum. Greater than 100 dB below rated output, 20 Hz - 20 KHz.


Normal: 50,000 ohm load;
Control By-Pass: 20,000 ohm load;
1.6 volts for 200 watts @ 8 ohms.

Slewing Rate: 8 volts per microsecond.

Damping Factor:

Greater than 80 to 1 KHz into 8 ohms;
Greater than 30 to 10 KHz into 8 ohms.

Channel Separation: Greater than 60 dB by IHF standards.

Connectors: Inputs: phono jacks. Outputs: Color coded 3-way binding posts with standard 3/4" spacing.

Dimensions: 19" wide; 14" deep; 7" high.

Weight: Shipping weight 59 lbs/27 kilos. Net weight 53 lbs/25 kilos.

Power Consumption: 120 VA quiescent; 17 amps maximum; 50/60 Hz, 120/240 VAC.

Designed by:

Wade Burns (Engineer, Dynaguard™), Jim Bongiorno, Erno Borbely, Harry Klaus (asst. circuitry), Hans Frank

Year Introduced:



Dynaco's last gasp; perhaps their greatest amplifier, this behemoth implemented a doubled output transistor configuration and fan along with a buffer stage bypass and the C-100 add-on power supply capacitor bank for unequalled drive and power capability. Built-in rack mounts, handles, and a sensitive LED power meter assembly added to the amplifier's no-nonsense appearance. Received rave reviews.

The C-100 energy storage unit, designed by Wade Burns. Picture from Ebay auction #386255002.

This page created and maintained by Greg Dunn.
Copyright © 2000 Greg Dunn